JPH11354100A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery equipped with a protective mechanism, that can remove the cause of heat generation by cutting off current when abnormal temperature rise occurs inside, including the case of passing of overcurrent and can prevent a rupture and the scattering of an inside filler in conjunction with it in advance, regardless of whether or not temperature rise occurs when internal pressure abnormally increases. SOLUTION: This battery is provided with a plate-like shape memory element 1 that has a through-hole and is formed from a Ti-Ni alloy, a conductive ball 3 that has a diameter larger than that of the hole and is so positioned as to plug the hole, and a plate-like bias spring 2 pressing the conductive ball 3 against the shape memory element 1 at all times. In addition, the battery has a protective mechanism that can prevent abnormal inside temperature rise due to the passage of an overcurrent and a rupture due to the increase of internal pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery, and more particularly, to a battery having a function of preventing abnormal internal temperature rise due to overcurrent or the like and avoiding rupture due to internal pressure rise.

[0002]

2. Description of the Related Art A battery has conventionally been provided with a protection mechanism for an abnormal rise in internal temperature or an increase in internal pressure due to an overcurrent or other causes.

FIG. 2 is an explanatory view of the structure of a conventional battery. In FIG. 2, a protection mechanism for dealing with an abnormal situation such as a rise in internal temperature or a rise in internal pressure includes an overcurrent protection element 5 composed of a PTC element, an explosion-proof valve 6, and an exhaust hole 8. At normal temperature, the explosion-proof valve 6 and the exhaust hole 8 are closed.

[0004] A trace amount of carbonate is mixed in the cathode material inside the battery in advance, and a decomposition gas composed of carbon dioxide is generated in response to an abnormality in which the temperature inside the battery rises to a certain temperature or more. I have. That is, for abnormal heat generation of the battery due to a short circuit of the external circuit or the like, or overcurrent exceeding a certain level, the internal pressure is increased by generating the decomposition gas, the explosion-proof valve 6 and the exhaust hole 8 are opened, and the decomposition gas is discharged. In addition, the battery is prevented from being ruptured, and the internal filler accompanying the rupture is prevented. In addition to abnormal heat generation of the battery due to short-circuiting of an external circuit and the like, and overcurrent exceeding a certain level, the resistance of the overcurrent protection element increases and the current is cut off.

[0005]

However, in the conventional battery, there is a problem in that the number of components of the protection mechanism including the explosion-proof valve 6 and the overcurrent protection element 5 is large and the reliability of the respective connections is not high. was there.

The overcurrent protection element 5 is made of resin and carbon powder, and the melting point of the resin is set as the operating temperature. However, since the melting point of the resin is used as the operating temperature itself, it has been substantially difficult to reduce the error of the operating temperature to function. For this reason, in reality, it has not been possible to set a necessary and sufficient protective function corresponding to each type of battery or corresponding to the use environment.

[0007] In the conventional battery, the explosion-proof valve 6 is provided on the assumption that the internal pressure rises only with the rise of the internal temperature. Therefore, the internal pressure rises at a normal temperature. In an abnormal case, the explosion-proof valve 6 was configured not to operate.

An object of the present invention is to include a case where an overcurrent passes, and in a case where an abnormal temperature rise occurs in the inside, the current is cut off to eliminate a cause of heat generation and an internal pressure rises abnormally. In this case, it is an object of the present invention to provide a battery provided with a protection mechanism for preventing rupture and scattering of the internal filler accompanying the rupture irrespective of the presence or absence of a temperature rise.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a plate-shaped shape memory element made of a Ti-Ni alloy having a through hole, and a conductive material having a diameter larger than the hole and positioned to close the hole. And a plate-shaped bias spring that constantly presses the conductive ball against the shape memory element to prevent abnormal internal temperature rise due to passage of overcurrent or rupture due to internal pressure rise The battery has a protection mechanism.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram illustrating the operation of the battery protection mechanism according to the present invention. 1A shows a normal operation, FIG. 1B shows an abnormal rise in temperature, and FIG. 1C shows an abnormal rise in internal pressure. FIG.

In FIG. 1, a plate-shaped shape memory element 1, a conductive ball 3, and a bias spring 2 are used in combination for a protection mechanism of a battery. A conductive ball 3 is arranged between the shape memory element 1 and the bias spring 2, and the conductive ball 3 is constantly pressed toward the shape memory element 1 by the bias spring 2. The shape memory element 1 has 100
A Ti—Ni-based shape memory alloy that undergoes a phase transformation at a temperature of ° C. and changes its shape by passing through the temperature is used.

The plate-shaped shape memory element 1 has conductive balls 3
A smaller diameter is provided with a through hole, and the conductive ball 3 is located in this hole. The conductive balls 3
Since the hole is always held down by the bias spring 2, the hole of the shape memory element 1 is normally closed by the conductive ball 3, and airtightness is maintained.

Normally, the positive electrode lead 9 is in contact with the conductive ball 3 and is further connected to the bias spring 2 sequentially. In the battery shown in FIG. 1, the bias spring 2 serves as a positive electrode terminal as it is. The bias spring 2 has an exhaust hole 8
Is provided.

When the battery is functioning normally, the conductive ball 3 is biased by the bias spring 2 to the positive lead 9.
And the bias spring 2 is kept in conduction with the positive electrode lead 9 via the conductive ball 3 [FIG.
(A)].

However, when the temperature of the shape memory element rises to 100 ° C. or more due to internal heat generation of the battery due to an abnormality such as occurrence of an overcurrent, the current is interrupted [FIG.
(B)]. That is, in the shape memory element 1, the shape recovery due to the phase transformation occurs, the bias spring 2 is pushed up through the conductive ball 3, the conductive ball 3 separates from the positive electrode lead 9, and the conduction is interrupted. Disappears. This phenomenon does not depend on the presence or absence of an internal pressure change. By the way,
Since the Ti-Ni-based alloy has a specific resistance of 80-100 μΩ · cm, its cross-sectional area is selected according to the current value.
Overcurrent protection can be designed.

Even when the battery is heated from the outside and the temperature of the shape memory element 1 rises to 100 ° C. or higher, the shape memory element 1 pushes up the conductive ball 3 due to shape recovery [FIG. 1 (b)]. As a result, an increase in internal pressure is prevented in advance.

When the internal pressure of the battery rises, the conductive ball 3 which closes the hole of the shape memory element 1 and functions as a so-called explosion-proof valve, regardless of the temperature rise, Pushed up by. Then, the decomposed gas is discharged through an exhaust hole 8 provided in the bias spring 2. As a result, rupture of the battery, scattering of the internal filler, and the like are prevented.

The conductive ball 3 only has to close the hole formed in the shape memory element 1 and perform the function of a so-called explosion-proof valve as described above. Therefore, the conductive ball 3 does not have to be spherical in shape as long as it performs its function. If the shape of the hole formed in the shape memory element matches the cross-sectional shape of the conductive ball, the hole can be closed air-tightly, and if necessary, the air-tightness can be released, the conductive ball will have a conical shape, for example. Or a pyramid shape. In addition, the conductive ball 3 may be joined to the bias spring 2 to form an integral part due to its function.

By appropriately combining the shape memory element 1 and the spring force of the bias spring 2, rupture or the like can be avoided not only for an abnormal temperature rise but also for an abnormal rise in internal pressure independent of a temperature change. It is effective for

The battery according to the present invention has a simple structure with a small number of parts of the shape memory element 1, the conductive ball 3, and the bias spring 2, can control the composition, and can arbitrarily set the phase transformation temperature. A highly reliable shape change operation is realized. According to the present invention, it is also possible to set an appropriate protective function in accordance with each type of battery or in accordance with the use environment.

[0022]

As described above, according to the present invention, when an abnormal temperature rise occurs inside, including the case where an overcurrent passes, the current is cut off and the internal pressure rises abnormally. In this case, a battery having a protection mechanism for preventing the explosion and the scattering of the internal filler due to the explosion can be obtained by operating the function of a so-called explosion-proof valve.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the operation of a battery protection mechanism according to the present invention.
1A shows a normal operation, FIG. 1B shows an abnormal rise in temperature, and FIG. 1C shows an abnormal rise in internal pressure. FIG.

FIG. 2 is an explanatory view of the structure of a conventional battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shape memory element 2 Bias spring 3 Conductive ball 5 Overcurrent protection element 6 Explosion-proof valve 7 Gasket 8 Exhaust hole 9 Positive electrode lead 11 Positive electrode terminal 12 Positive electrode plate 13 Negative electrode plate 14 Separator 15 Insulating plate 16 Case

Claims (2)

[Claims] 1. A battery having a protection mechanism for preventing at least one of an abnormal temperature rise due to the passage of an overcurrent and an abnormal rise in an internal pressure, wherein a plate-shaped shape memory element having a through hole is provided. And a conductive ball having a diameter larger than the hole and positioned to close the hole,
A battery comprising a protection mechanism including a plate-shaped bias spring that constantly presses the conductive ball toward the shape memory element. 2. The battery according to claim 1, wherein the shape memory element is made of a Ti—Ni alloy.